[OLPC Engineering] [Techteam] New F14-arm build os21
pgf at laptop.org
Thu Jul 21 07:21:07 EDT 2011
> On Thu, Jul 21, 2011 at 12:14:14AM -0400, Martin Langhoff wrote:
> > On Wed, Jul 20, 2011 at 6:04 AM, Martin Langhoff <martin at laptop.org> wrote:
> > > On Wed, Jul 20, 2011 at 6:02 AM, Martin Langhoff <martin at laptop.org> wrote:
> > >> ?- Updates olpc-utils to disable X zapping and fix serial port terminal
> > >
> > > Initial testing seems to indicate serial port needs a bit more
> > > attention. I've also tested it with a newer kernel containing Paul's
> > > tty config fix, and it doesn't make a difference.
> > Looking at it again -- there is no apparent problem with using the
> > serial port, only an early msg in var/log/messages
> > Jul 21 04:07:36 localhost init: ttySx main process (33) terminated
> > with status 1
> I looked into this.
> /etc/init/ttyS.conf says "start on startup", but if it is changed to
> "start on runlevel " this strange message goes away. Perhaps it
that would probably be okay. when i changed our conf file to "start on
startup" a year or more ago, it was to get the serial port up as soon
as possible, because i was tired of not having it while the system booted.
(it was being treated as a normal user getty before that, i think.)
> is caused by some interaction with upstart's init, or perhaps we are not
> following best practices in ttyS.conf.
> (We have our own ttyS.conf, but curiously /etc/init/serial.conf might
> have been starting a process, but it says it requires ttyS2 to be the
> last or primary console in the kernel command line, and for it to be
> listed in /etc/securetty. Doing those things doesn't cause serial.conf
> to start a process though.)
> > But nothing seems to be broken
> > - shutdown/reboot works correctly (and the plymouth workaround has
> > been removed)
> > - switch to gnome / sugar works correctly
> > - bash is respawned correctly if you exit
> My gut feel is that we still have something lurking here, but nothing we
> ship at the moment tries modem control on /dev/ttyS2. Not even
> ModemManager, according to strace. (Pity it doesn't ignore USB serial
> adapters as well.)
> I looked briefly at the serial/pxa driver. When a user process
> configures for modem control on /dev/ttyS2 via termios, the upshot is
> the setting of bit AFE (Auto-flow Control Enable) in the UART MCR (modem
> control register). Good.
> During serial_pxa_startup, /dev/ttyS3 is configured for AFE
> automatically. But I didn't see any obvious way at mmp2_add_uart time
> to tell the driver not to bother setting UART_MCR_AFE for /dev/ttyS2.
> The control lines themselves aren't exposed, which is presumably why
> threads that do I/O hang.
> But hey, the same thing happens on XO-1.5, just tested ... so we're good
> to go. ;-)
> James Cameron
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paul fox, pgf at laptop.org
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